A conventional sensor apparatus of this kind is described with reference to a drawing. FIG. 5 is an electric circuit diagram showing the conventional sensor apparatus.
As shown in FIG. 5, the sensor apparatus includes: drive circuit sections 1A, 1B for outputting drive signals that drive detection device 2; and detection circuit sections 3A, 3B for fetching response signals from detection device 2 and outputting the response signals. The sensor apparatus further includes: processing circuit sections 4A, 4B for fetching sensor signals from the response signals and outputting the sense signals from first output terminals 5A, 5B; and failure diagnosis circuit 6 for outputting a failure detection signal from second output terminal 7.
At least any one of drive circuit sections 1A, 1B, detection device 2, detection circuit sections 3A, 3B and processing circuit sections 4A, 4B is set as an object of failure diagnosis and referred to as a failure diagnosis object section. Failure diagnosis circuit 6 determines whether the failure diagnosis object section is normal or abnormal, and outputs a failure detection signal from second output terminal 7 in the case of determining abnormality.
As related art document information concerning this application, for example, Unexamined Japanese Patent Publication No. 2004-301512 (Patent Document 1) is known. Such a conventional sensor apparatus has had a problem with improvement in reliability under abnormality occurrence condition.
Specifically, in the above conventional configuration, even though abnormality of the failure diagnosis object section has been confirmed by failure diagnosis circuit 6, outputting of the failure detection signal from second output terminal 7 is delayed due to some kind of defect, and hence a sense signal determined as one under abnormal condition may be used for control of a controlled object such as an automobile. Further, on controlled object side such as an automobile, the sense signal determined as one under abnormal condition may be erroneously used for control of the controlled object due to some kind of defect, thereby causing a problem with improvement in reliability.